Screw-type compression devices for compressing bone fractures have been used for years and are well known to persons skilled in the arts of orthopedic surgery and designing and manufacturing orthopedic surgical equipment. In fact, screw-type compression devices, commonly called compression hip screws, have remained virtually unchanged for many years. These devices have proven to be useful in providing necessary fixation of bone sections in fractured hips so that they can heal properly. These devices are normally left in place after the fracture has healed.
In the design of conventional screw-type compression devices, the head of the compressing screw is located at the outer surface of the device. This configuration works well as long as the head of the compressing screw remains in a fixed position relative to the outer surface of the device. However, the head of the compressing screw normally slides away from the surface of the device as a normal result of healing. This movement of the compressing screw is a desirable element of conventional devices since an otherwise fixed device would retard the normal healing process. However, full sliding movement of the compressing screw has a tendency to irritate surrounding soft tissue in some patients.
This problem is considered to be a minor nuisance that is handled several ways. The compressing screw is surgically retightened or the end of the compressing screw is covered by a substance such as bone cement. Alternatively, the compressing screw can be surgically removed. Another solution is to remove the compressing screw immediately after the screw is tightened in order to avoid another surgical procedure. However, this latter solution generally requires that the patient be handled with extreme care following surgery to prevent the separation of the fracture until the bone fragments are adequately rejoined. If successful, the problem of soft tissue irritation is avoided. In summary, the current state of the art gives the surgeon a dilemma: he can leave the compression screw in and risk soft tissue irritation or he can take the screw out and risk disassembly of the fracture.
The purpose of this invention is to provide a solution to the above-described problem of soft tissue irritation during the use of screw-type compression devices, without requiring an additional surgical procedure or expose the patient to the risk of post-op fracture separation.